In general, a vehicle having mounted thereon a manual gear transmission capable of performing a manual gear shift is provided with a shift lever for shifting gear shift stages formed in the manual gear transmission by a driver. The vehicle is adapted to be changed in speed in response to the operation of the shift lever by the driver.
There is a possibility that the vehicle of this kind with the transmission mounted thereon is travelling at a gear shift stage different from a gear shift stage optimum with respect to the travelling state of the vehicle due to the fact that there are personal differences in selecting the gear shift stage and in timings of operating the gear shift. For example, when the driver is driving the vehicle at a gear shift stage lower than the optimum gear shift stage, the rotation speed of the engine tends to be unnecessarily increased, thereby leading to deterioration in fuel consumption.
For solving these problems, there has so far been known a gear shift indicating apparatus or a gear shift indicator (hereinafter simply referred to as “GSI”) which is designed to execute a gear shift indicating control for controlling to instruct the driver to take the optimum gear shift stage when a current gear shift stage is different from the optimum gear shift stage acquired from engine loads, vehicle speeds and the like (see for example Patent Document 1).
The GSI disclosed in the Patent Document 1 comprises a control unit for calculating the optimum gear shift stage in response to the travelling state of the vehicle, and a display unit provided in a combination meter. The display unit has a shift-up lamp for instructing the shift-up to the driver, and a shift-down lamp for instructing the shift-down to the driver. The control unit has a gear shift map the same as a known gear shift map to be referred when setting the gear shifts in the automatic transmission, and is designed to light on the display unit the shift-up lamp or the shift-down lamp for the driver to take the optimum gear shift stage when the optimum gear shift stage acquired from the gear shift map in accordance with the engine loads and the vehicle speeds is different from the current gear shift stage.
On the other hand, there is known, in a vehicle provided with an automatic transmission, a gear shift control apparatus which is designed to execute an AI (Artificial Intelligence) control of restricting the gear shift to a predetermined gear shift stage in response to the travelling state of the vehicle, thereby optimizing the gear shift control, enhancing drivability, and alleviating a burden on the driver to carry out the driving operation (see for example Patent Document 2).
The gear shift control apparatus disclosed in the Patent Document 2 is provided with a control unit for controlling the gear shift in accordance with the vehicle travelling environment and the driving operation. For example, the known gear shift control apparatus is adapted to prohibit the shift-up and hold the current gear shift stage in the case that the accelerator is abruptly operated to be closed when the vehicle is travelling on a corner and other sharply curved roads. This means that the known gear shift control apparatus can obtain an adequate engine brake at the time of the vehicle being travelling on the corner, and can generate no shift-down at the reaccelerating time of the vehicle, thereby making it possible to avoid what is called a busy shift to perform the shift-up or the shift-down operation in a short time. This leads to the fact that the known gear shift control apparatus can stabilize the gear shift stages and can make the driving operation easy at the time of the vehicle being travelling on the corner. Further, the control unit is operative to determine whether or not the vehicle is travelling on an uphill or a downhill in accordance with the throttle opening degree, the vehicle speed and the like. When the control unit determines that the vehicle is travelling on the uphill, the control unit is operative to suppress unnecessary shift-up for the purpose of obtaining at all times a suitable driving force. When, on the other hand, the control unit determines that the vehicle is travelling on the downhill, the control unit is operative to automatically shift-down in order to obtain an appropriate brake force from a driving source.
As previously mentioned, the gear shift control apparatus disclosed in the Patent Document 2 is provided in the vehicle equipped with the automatic transmission and operative to restrict the gear shift stage in response to the travelling state of the vehicle, thereby executing the AI control to optimize the gear shift control, and thereby preventing the gear shift not to be desired by the driver and alleviating the burden on the driver to carry out the driving operation.